Aircraft propulsion system including a heat exchanger system

ABSTRACT

An aircraft propulsion system, including a turbojet and a heat exchanger system which includes a main heat exchanger, a hot air supply pipe, a transfer pipe transferring hot air to an air management system, a main supply pipe supplying cold air from the fan duct, an evacuation pipe expelling air to the outside, a sub heat exchanger with a high pressure pipe going therethrough, a sub supply pipe supplying cold air and including a sub regulating valve, a sub evacuation pipe expelling air, a temperature sensor, and a controller controlling the system according to the temperature measured The sub regulating valve comprises a door articulated between closed and open positions, a return spring constraining the door in the open position, and a realizing system, controlled by the controller, mobile between a blocking position and a realizing position in which the door is released to move to the open position.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims the benefit of the European patent applicationNo. 19162028.5 filed on Mar. 11, 2019, the entire disclosures of whichare incorporated herein by way of reference.

FIELD OF THE INVENTION

The present invention relates to an aircraft propulsion system includinga heat exchanger system, together with an aircraft including at leastone such propulsion system.

BACKGROUND OF THE INVENTION

In order to supply hot air whether for a system of air, conditioned soas to guarantee the comfort of the passengers, or for a de-icing systemfor de-icing the outside surfaces of an aircraft, this system includes aheat exchanger system, which is schematically illustrated in FIG. 4.

The heat exchanger system 500 is disposed in the vicinity of theturbojet of the aircraft and includes a heat exchanger 502. The turbojetis fixed to the structure of the wing due to a pylon, and the heatexchanger 502 is located between the pylon and the pylon fairing.

The heat exchanger 502 is supplied with hot air through a first supplypipe 504, which bleeds hot air from the high-pressure stage 506 or atthe intermediate pressure stage 508 of the turbojet, respectivelythrough a first valve 510 and a second valve 512. The first supply pipe504 also includes a regulating valve 514, which enables regulation ofthe pressure at the inlet of the heat exchanger 502.

The heat exchanger 502 is supplied with cold air by a second supply pipe516, which bleeds cold air from the fan duct of the turbojet. The secondsupply pipe 516 also includes a regulating valve 518, which regulatesthe quantity of cold air introduced into the heat exchanger 502 so as toregulate the temperature of the hot air exiting the heat exchanger 502.

After having passed through the heat exchanger 502, the cold air, whichhas been heated, is expelled to the outside through an evacuation pipe520.

After having passed through the heat exchanger 502, the hot air, whichhas been cooled, is directed through a transfer pipe 522 to the airmanagement systems like the air conditioning system or the de-icingsystem.

The heat exchanger system 500 includes a temperature sensor 523, whichmeasures the temperature of the hot air exiting the heat exchanger 502and a control unit 524, or controller, which controls the valvesaccording to the temperature measured by the temperature sensor 523 andthe temperature desired for the hot air exiting the heat exchanger 502.

The heat exchanger 502 is with cross flow, that is to say, the hot airand the cold air enter the heat exchanger 502 and exit the heatexchanger 502 along two globally perpendicular directions.

In case the temperature sensor 523 detects that the temperatureincreases abnormally, it is necessary to regulate the flow of hot airflowing in the heat exchanger 502. The actual solution is to oversizethe heat exchanger 502, but in this case, it is heavier and takes morespace.

EP-A-0 934 876, US-A-2012/045317 and WO-A-2018/002855 disclosepropulsion systems of the state of the art.

The size of the turbojet increases due to the necessity to increase thebypass ratio and the overall pressure ratio. Due to this increasing ofthe turbojet, the space allocated to the heat exchanger 502 is reducedand the air exhaust of the heat exchanger 502 is close to the leadingedge of the wing, creating perturbations to the boundary layer.

SUMMARY OF THE INVENTION

An aim of the present invention is to propose an aircraft propulsionsystem including a heat exchanger system, which is less bulky and thusenables better integration in the propulsion system.

To that effect, an aircraft propulsion system is proposed, the aircraftpropulsion system including a turbojet including an intermediatepressure stage and a high-pressure stage, a fan duct, and a heatexchanger system which includes:

-   -   a main heat exchanger including a main hot supply connection, a        main hot transfer connection pneumatically connected to the main        hot supply connection through the main heat exchanger, a main        cold supply connection and a main cold evacuation connection        pneumatically connected to the main cold supply connection        through the main heat exchanger,    -   a supply pipe which is connected to the main hot supply        connection, and which supplies the heat exchanger with the hot        air, and which includes a regulating valve,    -   a high pressure pipe which bleeds hot air from the high-pressure        stage through a first valve,    -   an intermediate pressure pipe which bleeds hot air from the        intermediate pressure stage through a second valve, wherein the        high-pressure pipe and the intermediate pressure pipe are        connected to the inlet of the regulating valve,    -   a transfer pipe which is connected to the main hot transfer        connection, and which is adapted to transfer the hot air that        has passed through the main heat exchanger to an air management        system of the aircraft,    -   a main supply pipe which is connected to the main cold supply        connection, which supplies the main heat exchanger with cold air        from the fan duct, and which includes a main regulating valve,    -   an evacuation pipe which is connected to the main cold        evacuation connection and is adapted to expel the air to the        outside,    -   a sub heat exchanger including a sub hot supply connection, a        sub hot transfer connection pneumatically connected to the sub        supply connection through the sub heat exchanger, a sub cold        supply connection and a sub cold evacuation connection        pneumatically connected to the sub cold supply connection        through the sub heat exchanger, wherein the high pressure pipe        issued from the first valve goes through the sub heat exchanger        between the sub hot supply connection and the sub hot transfer        connection,    -   a sub supply pipe which is connected to the sub cold supply        connection, which supplies the sub heat exchanger with cold air        from the fan duct and which includes a sub regulating valve,    -   a sub evacuation pipe which is connected to the sub cold        evacuation connection and expels the air to the fan duct,    -   a temperature sensor, which measures the temperature of the hot        air exiting the main heat exchanger through the transfer pipe,        and    -   a control unit which controls the main regulating valve and the        sub regulating valve according to the temperature measured by        the temperature sensor and the temperature desired for the hot        air exiting the main heat exchanger through the transfer pipe,

wherein the sub regulating valve comprises a door mounted articulatedbetween a closed position in which it closes the sub supply pipe toprevent the passage of the cold air through the sub supply pipe, and anopen position in which it releases the sub supply pipe to authorize thepassage of the cold air through the sub supply pipe, a return springwhich constrains the door in the open position, and a realizing system,controlled by the control unit, which is mobile between a blockingposition in which it blocks the door in the closed position, and arealizing position in which it releases the door which is free to moveto the open position.

This embodiment allows a supplementary cold air flow if necessary.

Advantageously, the propulsion system includes a pylon with a primarystructure which supports the turbojet, the main heat exchanger islocated above the primary structure and in the fan duct and the sub heatexchanger is below the primary structure and in the fan duct.

The invention also proposes an aircraft including at least onepropulsion system according to one of the preceding variants.

BRIEF DESCRIPTION OF THE DRAWINGS

The aforementioned characteristics of the invention, as well as others,will emerge more clearly on reading the following description of anembodiment example, the description being made in relation to theattached drawings, among which:

FIG. 1 is a side view of an aircraft including a heat exchanger systemaccording to the invention,

FIG. 2 is a schematic illustration of a heat exchanger system accordingto the invention,

FIG. 3 shows a side view of the heat exchanger system according to theinvention in its environment, and

FIG. 4 is a schematic illustration of a heat exchanger system of thestate of the art.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the description that follows, the terms relating to a position aretaken with reference to an aircraft in normal flight position, that isto say, as illustrated on FIG. 1, and the positions “forward” and “aft”are taken in relation to the front and rear of the turbojet.

In the description that follows, and by convention, X is thelongitudinal axis of the turbojet, which is parallel to the longitudinalaxis of the aircraft, Y is the transversal axis, which is horizontalwhen the aircraft is on the ground, and Z is the vertical axis, which isvertical when the aircraft is on the ground, these three directions X, Yand Z being orthogonal to each other.

FIG. 1 shows an aircraft 10, which includes a fuselage 11, on eitherside of which a wing 13 is fastened that supports at least onepropulsion system 15 which is shown on FIG. 3 and which includes a pylon12 and a turbojet 70. The pylon 12 is fastened under the wing 13 andsupports the turbojet 70, which conventionally includes a compressionstage 72 and a fan duct 74. The pylon 12 includes a primary structure50, which is fastened at its upper part to the structure of the wing 13and which supports the turbojet 70 through different fastening points.The primary structure 50 is disposed above the turbojet 70 and its frontedge is attached to the turbojet 70 inside the fan duct 74.

The compression stage 72 includes a high-pressure stage 206 and anintermediate pressure stage 208. For example, in cruise conditions at41000 ft, the intermediate pressure at 205° C. is 35 psia, and the highpressure at 517° C. is 174 psia.

The aircraft 10 includes an air management system like, for example, anair conditioning system and/or a de-icing system.

The propulsion system 15 also includes a nacelle 14, which includes afairing 76, which surrounds the turbojet 70, and an aerodynamic fairingof the pylon 12, which surrounds the primary structure 50.

FIG. 2 shows a heat exchanger system 200 according to the invention.

The heat exchanger system 200 includes a main heat exchanger 202 whichcomprises a main hot supply connection 201, a main hot transferconnection 203 pneumatically connected to the main supply connection 201through the main heat exchanger 202, a main cold supply connection 205and a main cold evacuation connection 207 pneumatically connected to themain cold supply connection 205 through the main heat exchanger 202.

The heat exchanger system 200 includes a supply pipe 204 connected tothe main hot supply connection 201 and which supplies the main heatexchanger 202 with hot air and which includes a regulating valve 214,which enables regulation of the pressure at the hot supply connection201.

The heat exchanger system 200 includes a high-pressure pipe 250 whichbleeds hot air from the high-pressure stage 206 through a first valve210.

The heat exchanger system 200 includes an intermediate pressure pipe 252which bleeds hot air from the intermediate pressure stage 208 through asecond valve 212.

The high-pressure pipe 250 and the intermediate pressure pipe 252 areconnected together to the inlet of the regulating valve 214.

The heat exchanger system 200 includes a main supply pipe 216 connectedto the main cold supply connection 205 and which supplies the main heatexchanger 202 with cold air and which bleeds cold air from the fan duct74 of the turbojet 70. The main supply pipe 216 also includes a mainregulating valve 218, which regulates the quantity of cold airintroduced into the main heat exchanger 202 so as to regulate thetemperature of the hot air exiting the main heat exchanger 202.

The heat exchanger system 200 includes an evacuation pipe 220 connectedto the main cold evacuation connection 207. After having passed throughthe main heat exchanger 202, the cold air, which has been heated, isexpelled to the outside through the evacuation pipe 220.

The heat exchanger system 200 includes a transfer pipe 222 connected tothe main hot transfer connection 203. After having passed through themain heat exchanger 202, the hot air, which has been cooled, is directedthrough the transfer pipe 222 to the air management systems like the airconditioning system or the de-icing system.

The heat exchanger system 200 includes a temperature sensor 223, whichmeasures the temperature of the hot air exiting the main heat exchanger202 through the transfer pipe 222 and a control unit 224, or controller,which controls the valves according to the temperature measured by thetemperature sensor 223 and the temperature desired for the hot airexiting the main heat exchanger 202 through the transfer pipe 222.

The main heat exchanger 202 is here with cross flows, that is to say,the hot air and the cold air enter the main heat exchanger 202 and exitthe main heat exchanger 202 along two globally perpendicular directions.But in another embodiment, the passage of the hot air through the mainheat exchanger 202 from the supply pipe 204 to the transfer pipe 222takes place along a first transfer direction and the passage of the coldair through the main heat exchanger 202 from the main supply pipe 216 tothe evacuation pipe 220 takes place along a second transfer directionparallel to the first transfer direction but in the opposite direction.

The heat exchanger system 200 includes also a sub heat exchanger 230connected between the first valve 210 and the regulating valve 214 onthe high-pressure pipe 250.

The sub heat exchanger 230 comprises a sub hot supply connection 231, asub hot transfer connection 233 pneumatically connected to the subsupply connection 231 through the sub heat exchanger 230, a sub coldsupply connection 235 and a sub cold evacuation connection 237pneumatically connected to the sub cold supply connection 235 throughthe sub heat exchanger 230.

The high-pressure pipe 250 issued from the first valve 210 goes throughthe sub heat exchanger 230 between the sub hot supply connection 231 andthe sub hot transfer connection 233.

The heat exchanger system 200 includes also a sub supply pipe 232connected to the sub cold supply connection 235 and which supplies thesub heat exchanger 230 with cold air and which bleeds cold air from thefan duct 74 of the turbojet 70. The sub supply pipe 232 also includes asub regulating valve 234.

The heat exchanger system 200 includes a sub evacuation pipe 236connected to the sub cold evacuation connection 237. After having passedthrough the sub heat exchanger 230, the cold air, which has been heated,is expelled to the fan duct 74 through the sub evacuation pipe 236.

The sub regulating valve 234 takes here the form of a scoop including adoor 240 mounted articulated between a closed position in which itcloses the sub supply pipe 232 to prevent the passage of the cold airthrough the sub supply pipe 232, and an open position in which itreleases the sub supply pipe 232 to authorize the passage of the coldair through the sub supply pipe 232.

The detail I in FIG. 2 shows the door 240 in the closed position and thedetail II in FIG. 2 shows the door 240 in the open position.

The sub regulating valve 234 comprises a return spring 242 whichconstrains the door 240 in the open position.

The sub regulating valve 234 comprises a realizing system 244 which ismobile between a blocking position in which it blocks the door 240 inthe closed position, and a realizing position in which it releases thedoor 240 which is free to move to the open position.

The realizing system 244 is also controlled by the control unit 224 andis, for example, an electromagnet.

The main heat exchanger 202 is sized for the intermediate pressure stage208 and for the high-pressure stage 206 and in the normal conditions,the sub heat exchanger 230 is not used.

In the normal conditions, the hot air comes from the intermediatepressure stage 208 and eventually from the high-pressure stage 206, goesthrough the regulating valve 214 and the main heat exchanger 202. Inthese conditions, the hot air coming from the high-pressure stage 206flows through the sub heat exchanger 230 but the door 240 is closed andno cold air flows through the sub heat exchanger 230 to cool the hot airand the regulation is similar to the regulation of the prior artembodiment.

In case of abnormal conditions, when it is necessary to increase thecooling of the hot air coming from the high-pressure stage 206, thecontrol unit 224 commands the realizing system 244 to move it from theblocking position to the realizing position.

Then the door 240 is free to move and the return spring 242 acts on thedoor 240 to move it into the open position. Thus, additional cold aircan be accepted in the sub supply pipe 232 and used in the sub heatexchanger 230.

The return of the door 240 in the closed position can be done manuallyat the next landing.

In the embodiment shown on FIG. 2, the sub heat exchanger 230 is withcross-flow flows but, in another embodiment, not illustrated, it can bewith parallel flows.

FIG. 3 shows the heat exchanger system 200 of the propulsion system 15in its environment.

The main heat exchanger 202 is located above the primary structure 50and in the fan duct 74 and the sub heat exchanger 230 is below theprimary structure 50 and in the fan duct 74. More precisely, the mainheat exchanger 202 is located between the pylon and the pylon fairing.

The primary structure 50 comprises a window through which the supplypipe 204 goes through to connect itself with the high-pressure pipe 250and the intermediate pressure pipe 252.

In the embodiment shown on FIG. 3, the regulating valve 214 is alsoarranged below the primary structure 50.

The main regulating valve 218 can take also the form of a scoopincluding a door, which is mobile between an open position in which itdoes not blank off the scoop and a closed position in which it blanksoff the scoop so as to regulate the quantity of cold air captured by thescoop. The door is motorized so as to ensure its movement and the motoris controlled by the control unit 224 and the door acts as a valve.

Each scoop is oriented so as to be able to capture the cold air thatcirculates in the fan duct 74.

The new implementation allows a design of the main heat exchanger withlow bleed air side pressure drop. This lower pressure drop allows animprovement engine start performance due to higher pressure delivered tothe starter turbine, a higher inlet pressure to air conditioning packallowing the pack to operate with less ram air and thus reducing inducedram drag, and the challenging of the position of the intermediatepressure stage port, using a lower compressor stage that improves enginespecific fuel consumption.

While at least one exemplary embodiment of the present invention(s) isdisclosed herein, it should be understood that modifications,substitutions and alternatives may be apparent to one of ordinary skillin the art and can be made without departing from the scope of thisdisclosure. This disclosure is intended to cover any adaptations orvariations of the exemplary embodiment(s). In addition, in thisdisclosure, the terms “comprise” or “comprising” do not exclude otherelements or steps, the terms “a” or “one” do not exclude a pluralnumber, and the term “or” means either or both. Furthermore,characteristics or steps which have been described may also be used incombination with other characteristics or steps and in any order unlessthe disclosure or context suggests otherwise. This disclosure herebyincorporates by reference the complete disclosure of any patent orapplication from which it claims benefit or priority.

1. A propulsion system of an aircraft, said propulsion system includinga turbojet including an intermediate pressure stage and a high-pressurestage, a fan duct, and a heat exchanger system, which includes: a mainheat exchanger including a main hot supply connection, a main hottransfer connection pneumatically connected to the main hot supplyconnection through the main heat exchanger, a main cold supplyconnection and a main cold evacuation connection pneumatically connectedto the main cold supply connection through the main heat exchanger, asupply pipe which is connected to the main hot supply connection, andwhich supplies the main heat exchanger with hot air, and which includesa regulating valve, a high-pressure pipe which bleeds hot air from thehigh-pressure stage through a first valve, an intermediate pressure pipewhich bleeds hot air from the intermediate pressure stage through asecond valve, wherein the high-pressure pipe and the intermediatepressure pipe are connected to an inlet of the regulating valve, atransfer pipe which is connected to the main hot transfer connection,and which is configured to transfer the hot air that has passed throughthe main heat exchanger to an air management system of the aircraft, amain supply pipe which is connected to the main cold supply connection,which supplies the main heat exchanger with cold air from the fan duct,and which includes a main regulating valve, a main evacuation pipe whichis connected to the main cold evacuation connection and is configured toexpel the air to the outside, a sub heat exchanger including a sub hotsupply connection, a sub hot transfer connection pneumatically connectedto the sub hot supply connection through the sub heat exchanger, a subcold supply connection and a sub cold evacuation connectionpneumatically connected to the sub cold supply connection through thesub heat exchanger, wherein the high pressure pipe issued from the firstvalve goes through the sub heat exchanger between the sub hot supplyconnection and the sub hot transfer connection, a sub supply pipe whichis connected to the sub cold supply connection, which supplies the subheat exchanger with cold air from the fan duct and which includes a subregulating valve, a sub evacuation pipe which is connected to the subcold evacuation connection and expels air to the fan duct, a temperaturesensor, which measures a temperature of the hot air exiting the mainheat exchanger through the transfer pipe, and a controller whichcontrols the main regulating valve and the sub regulating valveaccording to the temperature measured by the temperature sensor and atemperature desired for the hot air exiting the main heat exchangerthrough the transfer pipe, wherein the sub regulating valve comprises adoor mounted articulated between a closed position in which the doorcloses the sub supply pipe to prevent passage of the cold air throughthe sub supply pipe, and an open position in which the door releases thesub supply pipe to authorize the passage of the cold air through the subsupply pipe, a return spring which constrains the door in the openposition, and a realizing system, controlled by the controller, which ismobile between a blocking position in which the realizing system blocksthe door in the closed position, and a realizing position in which therealizing system releases the door which is free to move to the openposition.
 2. The propulsion system according to claim 1, furtherincluding a pylon with a primary structure, which supports the turbojet,wherein the main heat exchanger is located above the primary structureand in the fan duct and wherein the sub heat exchanger is below theprimary structure and in the fan duct.
 3. An aircraft including at leastone propulsion system according to claim 1.